Role Of Mast Cells And Their Chymases In The Development Of Cardiac Hypertrophy
Funder
National Health and Medical Research Council
Funding Amount
$378,000.00
Summary
Cardiac hypertrophy or heart enlargement is an important risk factor in the eventual development of heart failure. It is now well known that heart enlargement can be produced by pressure overload of hypertension and-or by increased hormonal inputs directly to the heart. Angiotensin ll, a hormone that produces hypertension and heart enlargement, was previously thought only to be produced by the enzyme ACE. Although ACE inhibitors are widely used in treatment of hypertension and heart failure seve ....Cardiac hypertrophy or heart enlargement is an important risk factor in the eventual development of heart failure. It is now well known that heart enlargement can be produced by pressure overload of hypertension and-or by increased hormonal inputs directly to the heart. Angiotensin ll, a hormone that produces hypertension and heart enlargement, was previously thought only to be produced by the enzyme ACE. Although ACE inhibitors are widely used in treatment of hypertension and heart failure several studies now show that ACE inhibition only partially reduces angiotensin ll levels in humans. Our ecent studies suggest that the novel enzyme human chymase may be involved in regulating angiotensin ll levels in human tissues including the heart and blood vessels. The proposed studies seek to establish the role of chymase, and the cell type (mast cell) that elaborates it, in the development of cardiac hypertrophy.Read moreRead less
A Transgenic Mouse Model For Studying The Role Of Human Chymase In Regulating Tissue Angiotensin II Formation
Funder
National Health and Medical Research Council
Funding Amount
$536,063.00
Summary
Cardiac hypertrophy or heart enlargement is an important risk factor in the eventual development of heart failure. It is now well known that heart enlargement can be produced by pressure overload of hypertension and-or by increased hormonal inputs directly to the heart. Angiotensin II, a hormone that produces hypertension and heart enlargement, was previously thought only to be produced by the enzyme ACE. Although ACE inhibitors are widely used in treatment of hypertension and heart failure seve ....Cardiac hypertrophy or heart enlargement is an important risk factor in the eventual development of heart failure. It is now well known that heart enlargement can be produced by pressure overload of hypertension and-or by increased hormonal inputs directly to the heart. Angiotensin II, a hormone that produces hypertension and heart enlargement, was previously thought only to be produced by the enzyme ACE. Although ACE inhibitors are widely used in treatment of hypertension and heart failure several studies now show that ACE inhibition only partially reduces angiotensin II levels in humans. Our recent studies suggest that the novel enzyme human chymase may be involved in regulating angiotensin II levels in human tissues including the heart and blood vessels. By introducing a gene for human chymase in mice we plan to create a mouse model that allows us to understand the importance of human chymase in cardiovascular physiology and disease. This mouse model would not only show the involvement of human chymase in regulating heart and vessel angiotensin II levels and in the development of hypertension and heart enlargement but also will provide an animal model essential for the development of human chymase inhibitors.Read moreRead less
The Role Of Cbl Proteins In Mast Cell Signalling And Function.
Funder
National Health and Medical Research Council
Funding Amount
$239,250.00
Summary
Allergies such as asthma are caused by cells known as mast cells and basophils. These cells cause allergies because they possess pre-formed granules that contain mediators of allergic reactions, such as histamine, which are released when the cells are activated by allergens. Understanding how this activation occurs, and the biochemical mechanisms that allow the release of allergic mediators, are important steps towards identifying ways to intervene and control allergic responses. The key event t ....Allergies such as asthma are caused by cells known as mast cells and basophils. These cells cause allergies because they possess pre-formed granules that contain mediators of allergic reactions, such as histamine, which are released when the cells are activated by allergens. Understanding how this activation occurs, and the biochemical mechanisms that allow the release of allergic mediators, are important steps towards identifying ways to intervene and control allergic responses. The key event that activates the release of allergic mediators is the binding of environmental allergens to a particular type of antibody called IgE that can bind to a specific receptor on the surface of mast cells and basophils. These IgE-bound receptors transmit strong biochemical signals into the cell which causes a cascade of events resulting in many proteins being biochemically modified and recruited to sites of functional activity. One group of proteins, known as tyrosine kinases, are at the front line of this cascade and they function by targeting and modifying a wide range of other proteins so they become functionally active. Indeed if it were not for tyrosine kinases there would be no signal leading to degranulation of mast cells and basophils and therefore no allergic reactions. Therefore if it were possible to regulate the activity of tyrosine kinases we would be able to control the severity of allergic reactions. For many years we have been studying a protein called Cbl that functions in cells to negatively regulate many tyrosine kinases, including those present in mast cells and basophils. In this grant we aim to investigate whether by deregulating Cbl function in mast cells, derived from mice with mutated forms of Cbl, we can change the activity of tyrosine kinases and thus alter the magnitude of allergic responses. This will determine whether Cbl is candidate target protein for controlling allergies.Read moreRead less